The present disclosure relates generally to portable computing devices that interact with accessories and in particular to providing power from a portable device to an accessory during hibernation of the portable computing device.
In recent years, a number of portable computing devices (PCDs) have been developed. Examples of PCDs include portable media players, mobile phones, personal digital assistants (PDAs), portable e-mail devices, video game players, portable navigation units relying on Global Positioning System (GPS) satellite data, and multi-function devices that can integrate numerous functions such as media storage and playback, mobile phone, Internet access, e-mail, personal information management, game play, GPS/navigation capability, and the like. Examples of multi-function PCDs include various iPhone® and iPod® models manufactured and sold by Apple Inc., assignee of the present application, as well as other portable electronic devices made and sold by other manufactures and distributors under their respective brand names.
PCDs often obtain operating power from a battery within the device. Since a battery can provide only a finite amount of energy before requiring recharging or replacement, PCDs often employ various power-saving techniques to extend battery life. In one such technique, a PCD can be designed to transition into a “hibernation” mode in which some components of the device—such as components that consume significant fractions of the total energy (e.g., display screen, primary processor, etc.)—are powered down. Other components of the PCD can continue to receive power during hibernation, and these components generate wake-up events, or wake event signals, in response to which power is restored to the powered-down components. Thus, for example, the user can press a button on the PCD to wake it from hibernation, or a PCD can automatically wake itself from hibernation in response to an incoming phone call.
PCDs are frequently docked with other electronic devices, referred to herein as “accessories.” For example, from time to time, a user may dock a PCD with a personal computer to synchronize media content and/or metadata, personal data, and the like. A user may at other times dock the same PCD with other electronic devices, such as an in-vehicle media system, a speaker dock, or the like. Some accessories may provide power to the PCD from an external source, e.g., to recharge the PCD's battery or for use as operating power, and may also use power from an external source for their own operations. Other accessories draw their operating power from the PCD.